Get a links of pages.

tasks's get_internal_links get a links of html.
It doesn't check whether it is a sublink.
Merge remote-tracking branch 'origin/master'
Add test code.
Check link is internal url.
Refator probe.
Fix relative url working.
Test probe's all work.
Add probe tests.
Merge remote-tracking branch 'origin/master'

Hrad coding root page url.